A drone strike hit a car in Yemen on Saturday, killing four suspected al-Qaida militants, according to tribal officials.

The attack occurred in the southern province of Shabwa, a stronghold of al-Qaida's branch in Yemen.

This was the second such strike in a week. The United States is the only country known to be operating drones in Yemen. Previous strikes have also targeted the group, known as al-Qaida in the Arabian Peninsula. The U.S. considers AQAP al-Qaida's most dangerous offshoot.

The latest drone strike came as Yemen has been struggling with major political instability. Last week, Houthi rebels took over the residence of President Abd Rabbuh Mansour Hadi, prompting him and his Cabinet to resign.

The failure of a truce between the Houthi militia and the government of the U.S.-backed Hadi sparked reports that Washington would suspend counterterrorism operations until the situation stabilized.

But President Barack Obama dismissed those claims last Sunday, saying the United States would continue to pursue "high value targets inside Yemen."